In this article the actions taken in the area of epidemiological surveillance in Spain during the influenza pandemic and the recommendations drawn from them during the progression of the pandemic are reviewed. The performance of the Surveillance Subcommittee established in the National Influenza Preparedness and Response Plan was central to the coordination of these activities. The Surveillance Subcommittee was immediately activated when the alert was issued. Its role is also described in this review. The existence of a National Plan allowed a rapid and coordinated response after the alert declaration. The epidemiological and virological surveillance of the influenza pandemic was adapted to an evolving situation. In addition to routine influenza monitoring systems, new surveillance systems were put in place such as a case-based surveillance for community influenza cases and a case-based surveillance for severe cases and deaths due to the pandemic. Among the lessons learned from this pandemic, we would highlight the need to strengthen the timely analysis of data collected during an alert, the need to promote the exchange of information among public health and health care professionals, and to strengthen the response capacity in order to have resilient and consolidated public health structures for future health alerts.